Yeah...
Unfortunately, Facebook and Twitter have amplified Fox News (and conservative media's) reach beyond what one can see in the ratings.
And it's not Facebook and Twitter's fault. Conservatives through the radio and through email chains have been exploiting their audience for decades and decades.
It is absolutely Facebook and Twitter's fault.
They completely reworked how society communicates with itself with no regard for the consequences other than considerations for their business model. We are still in the part of the Algorithmic Revolution that is analogous to the part of the Industrial Revolution where all factories just dumped toxic waste into the air and water with no regard for anything but efficiency and profit.
What we are seeing right now works on an entirely different scale than email chains.